Device for Supplying Fuel to Engine

ABSTRACT

A merge and discharge unit has: a reservoir unit in which fuel can be collected; a first merge unit for merging into the reservoir unit the fuel from an upstream site upstream of the merge and discharge unit on a fuel supply route; a second merge unit for merging into the reservoir unit the fuel from a first fuel return route; a first discharge unit for discharging a portion of the fuel of the reservoir unit into a downstream site downstream of the merge and discharge unit on the fuel supply route; and a second discharge unit for discharging a remaining portion of the fuel of the reservoir unit into a second fuel return route.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for supplying fuel to anengine, the fuel supply device being provided with a fuel supply routefor supplying an engine with fuel collected in a fuel tank, and a filterand a first fuel pump being provided to the fuel supply route in thestated order from the upstream side of a fuel supply direction.

2. Description of the Related Art

In a fuel supply device of such description, impurities included in thefuel are removed by the filter provided to the fuel supply route, andthe fuel from which the impurities have been removed is supplied to theengine. Also, a fuel return route for returning fuel coming from theengine to the fuel tank is provided, so that surplus fuel in the engineis returned to the fuel tank by the fuel return route.

In the fuel supply device of such description, although the impuritiesare removed by the filter, in a case where low-temperature fuel is beingsupplied to the filter, such as initial start-up of the engine when in acold climate, a problem emerges in that deposited matter or the like iscreated from the fuel and the filter is clogged by the deposited matter.

In view whereof, in a conventional fuel supply device, aninterconnecting flow path that creates communication between a midwaysite of the fuel supply route and a midway site of the fuel return routeis provided, and a circulation valve of a temperature-sensitivedisplacement type is provided to the interconnecting flow path (see, forexample, Japanese Laid-open Patent Application 2007-16658).

In the apparatus described in Japanese Laid-open Patent Application2007-16658, the circulation valve opens the interconnecting flow path ina case where the fuel temperature is less than a predeterminedtemperature, whereby the comparatively higher-temperature fuel returningfrom the engine to the fuel tank is admixed into the fuel coming fromthe fuel tank and is supplied to the filter. The temperature of the fuelbeing supplied to the filter is thereby elevated, thus preventingclogging of the filter. Also, the circulation valve closes off theinterconnecting flow path in a case where the fuel temperature is thepredetermined value or greater, whereby the full amount of surplus fuelcoming from the engine is returned to the fuel tank.

SUMMARY OF THE INVENTION

In the apparatus described in Japanese Laid-open patent Application2007-16658, because preventing the clogging of the filter necessitatesthe furnishing of the circulation valve, which has atemperature-sensitivity displacement body made of a bimetal or the like,there is a corresponding increase in costs and in the complexity of theconfiguration.

In view of the foregoing, there has been demand for a fuel supply devicefor an engine that makes it possible to prevent clogging of a filter.

A device for supplying fuel to an engine, as in the present invention,comprises:

a fuel tank;

a fuel supply route for supplying to the engine fuel that has beencollected in the tank;

a filter provided to the fuel supply route;

a first fuel pump provided downstream of the filter in a fuel supplydirection on the fuel supply route;

a merge and discharge unit for merging and discharging fuel, the mergeand discharge unit being provided to a site between the fuel tank andthe filter on the fuel supply route;

a first fuel return route for returning the fuel of the engine to themerge and discharge unit; and

a second fuel return route for returning to the fuel tank the fueldischarged from the merge and discharge unit;

wherein:

the merge and discharge unit has: a reservoir unit in which fuel can becollected; a first merge unit for merging into the reservoir unit thefuel from a site upstream of the merge and discharge unit on the fuelsupply route; a second merge unit for merging into the reservoir unitthe fuel from the first fuel return route; a first discharge unit fordischarging a portion of the fuel in the reservoir unit to a sitedownstream of the merge and discharge unit on the fuel supply route; anda second discharge unit for discharging a remaining portion of the fuelin the reservoir unit into the second fuel return route.

According to this characteristic configuration, the fuel from the fueltank is supplied to the merge and discharge unit by the upstream site ofthe fuel supply route, and the fuel from the engine is returned to themerge and discharge unit by the first fuel return route. In the mergeand discharge unit, the fuel from the fuel tank is supplied to thereservoir unit by the first merge unit, the fuel from the engine ismerged into the reservoir unit by the second merge unit, and the mergedfuel is collected in the reservoir unit. Then, in the merge anddischarge unit, a portion of the fuel collected in the reservoir unit isdischarged to the downstream site of the fuel supply route by the firstdischarge unit, and a remaining portion is discharged to the second fuelreturn route by the second discharge unit.

In this manner, the merge and discharge unit makes it possible to mergethe fuel from the engine into the fuel from the fuel tank, and possibleto supply the merged fuel to the filter by way of the downstream site ofthe fuel supply route. Thus, even at such times as the initial start-upof the engine in a cold climate, it is accordingly possible to mergefuel that has been heated by heat generated from the engine or the likeinto the low-temperature fuel from the fuel tank and supplycomparatively high-temperature fuel to the filter, thus making itpossible to prevent clogging of the filter. As a result, a circulationvalve can be obviated; only the merge and discharge unit need beprovided, thus making it possible to prevent clogging of the filterwithout incurring an increase in cost or in complexity of theconfiguration.

However, of the fuel that is collected in the reservoir unit of themerge and discharge unit, a remaining portion other than what isdischarged to the downstream site of the fuel supply route is dischargedto the second fuel return route by the second discharge unit and isreturned to the fuel tank. This makes it possible to also properlyreturn surplus fuel of the engine to the fuel tank, while it is alsopossible to prevent clogging of the filter.

In the foregoing configuration, preferably, the amount of fueldischarged from the second discharge unit is less than the amount offuel discharged from the first discharge unit.

According to this characteristic configuration, of the fuel that iscollected in the reservoir unit in the merge and discharge unit, theflow rate of fuel discharged from the second discharge unit and returnedto the fuel tank is less than the flow rate of fuel discharged from thefirst discharge unit and supplied to the filter and to the engine.Because the flow rate of fuel supplied to the merge and discharge unitby the upstream site of the fuel supply route is an amount correspondingto the flow rate of fuel returned to the fuel tank from the merge anddischarge unit, it is possible to also lessen the flow rate of fuelsupplied to the merge and discharge unit from the fuel tank. This makesit possible to further increase the flow rate by which the fuel from theengine is merged into the fuel from the fuel tank, and possible toproperly elevate the fuel temperature of the fuel being supplied to thefilter, thus properly preventing clogging of the filter.

In the foregoing configuration, preferably, in causing the amount offuel discharged from the second discharge unit to be less than theamount of fuel discharged from the first discharge unit, a constrictedsite where the flow path cross-sectional area is less than that of thefirst discharge unit is provided to the second discharge unit, or aconstricted site where the flow path cross-sectional area is less thanthat of the downstream site on the fuel supply route is provided to thesecond fuel return route.

According to this characteristic configuration, for example, causing theflow path cross-sectional area of the second discharge unit to be lessthan the flow path cross-sectional area of the first discharge unitmakes it possible to provide the constricted site to the seconddischarge unit. Similarly, causing the flow path cross-sectional area ofthe second fuel return route to be less than the flow pathcross-sectional area of the downstream site on the fuel supply routemakes it possible to provide the constricted site to the second fuelreturn route.

Merely by thus employing the simple configuration of providing theconstricted site to the second discharge unit or the second fuel returnroute, it is possible to cause the amount of fuel discharged from thesecond discharge unit to be less than the amount of fuel discharged fromthe first discharge unit.

In the foregoing configuration, preferably, the first merge unit, thesecond merge unit, and the first discharge unit of the merge anddischarge unit are arranged in sites below the reservoir unit, and thesecond discharge unit is arranged at a site above the reservoir unit.

According to this characteristic configuration, in a case where air isincluded in the fuel, the supply of the fuel to the reservoir unit makesit possible for the air included in the fuel to rise to the site abovethe reservoir unit and be discharged from the second discharge unit.Thus, even when air is included in the fuel being supplied to theengine, this makes it possible to properly remove the air with the mergeand discharge unit.

In the foregoing configuration, preferably, a moisture removal unit forremoving moisture included in the fuel is arranged at a site between thefuel tank and the merge and discharge unit on the fuel supply route.

According to this characteristic configuration, it is possible to supplyto the engine fuel after moisture include therein has been removed bythe moisture removal unit, and fuel that does not include moisture canbe properly supplied to the engine. Also, as described above, causingthe amount of fuel discharged from the second discharge unit to be lessthan the amount of fuel discharged from the first discharge unit makesit possible to lessen the flow rate of fuel supplied to the merge anddischarge unit by the upstream site of the fuel supply route, and thusit is possible to reduce the processing capability required for themoisture removal unit, and the size and cost of the moisture removalunit can be successfully lowered.

In the foregoing configuration, preferably, a cooling unit for coolingthe fuel is arranged at a site between the merge and discharge unit andthe filter on the fuel supply route.

According to this characteristic configuration, in a case where the fueltemperature is an excessively high temperature, cooling the fuel withthe cooling unit makes it possible to lower the fuel temperature of thefuel being supplied to the engine to a desired temperature range.Moreover, as described above, providing the merge and discharge unitcauses the fuel from the engine to be merged into the fuel from the fueltank, and thus in a case where, for example, the engine is continuouslyoperated, it is conceivably possible that the fuel temperature of thefuel being discharged from the merge and discharge unit may reach anexcessively high temperature. In view whereof, providing the coolingunit to the site between the merge and discharge unit and the filter onthe fuel supply route, as in this characteristic configuration, makes itpossible to cool the fuel temperature of the fuel being supplied to theengine to a desirable temperature range, even when the fuel temperatureof the fuel being discharged from the merge and discharge unit is anexcessively high temperature.

In the foregoing configuration, preferably, a moisture removal unit forremoving moisture included in the fuel, a second fuel pump, the mergeand discharge unit, a cooling unit for cooling the fuel, a third fuelpump, the filter, and the first fuel pump are provided to the fuelsupply route in the stated order from the upstream side in the fuelsupply direction.

According to this characteristic configuration, the moisture removalunit is provided to the upstream site on the fuel supply route, as isthe second fuel pump. Then, as described above, causing the amount offuel discharged from the second discharge unit to be less than theamount of fuel discharged from the first discharge unit makes itpossible to lessen the fuel flow rate being supplied to the merge anddischarge unit by the upstream site of the fuel supply route, and thusit is possible to reduce the processing capability required for themoisture removal unit, and the size and cost of the moisture removalunit can be successfully lowered, while also the capacity required forthe second fuel pump, too, can be reduced, and the size and cost of thesecond fuel pump can be successfully lowered. Additionally, because thecooling unit is also provided, the fuel temperature of the fuel beingsupplied to the engine can be cooled to a desired temperature range evenwhen the fuel temperature of the fuel being discharged from the mergeand discharge unit reaches an excessively high temperature, as describedabove.

A device for supplying fuel to an engine, as in the present invention,comprises:

a fuel tank, the fuel tank including:

a bottom;

a recessed reservoir unit for collecting fuel, the recessed reservoirunit being recessed so as to be lower than other portions on the bottom;

a covering for covering the recessed reservoir unit in a state where thefuel is permitted to flow into the recessed reservoir unit; and

an intake unit for taking in and drawing out fuel inside the fuel tank,above the bottom of the fuel tank.

According to this configuration, because the recessed reservoir unit isprovided to the bottom of the fuel tank, fuel can be kept collected inthe recessed reservoir unit even when there is a lesser amount of fuel.Also, because the covering covers the recessed reservoir unit, thecovering makes it possible to prevent the fuel that is collected in therecessed reservoir unit from flowing outwardly therefrom, even when thefuel tank is swung in the left/right direction and in the front/reardirection. The fuel can accordingly be kept collected in the recessedreservoir unit even when the fuel tank is swung in the left/rightdirection and in the front/rear direction in a case where there is alesser amount of fuel. Because the intake unit takes in and draws outthe fuel that is collected in the recessed reservoir unit, the fuel canbe properly taken in without also taking in air, even when there is alesser amount of fuel in the fuel tank.

In the foregoing configuration, preferably, the covering is adapted soas to cover a middle site of the recessed reservoir unit as seen in planview.

According to this configuration, because the covering covers the middlesite of the recessed reservoir unit, a spacing can be formed between anouter peripheral part of the covering and an inner peripheral part ofthe recessed reservoir unit, across the full length of the outerperiphery of the covering. Therefore, fuel can be permitted to flow intothe recessed reservoir unit from the spacing, and even when there is alesser amount of fuel, the fuel can be properly kept collected in therecessed reservoir unit.

In the foregoing configuration, preferably, the intake unit is supportedby the covering, and is configured so that the covering supporting theintake unit can be inserted into or removed from the fuel tank.

According to this configuration, merely mounting the covering supportingthe intake unit onto the fuel tank makes it possible for the intake unitand the covering to be mounted together, and allows for the intake unitand the covering to be easily mounted. In a case where the intake unitand the covering are to be removed, the intake unit and the covering cansimilarly be removed together. Moreover, because the intake unit issupported by the covering, merely adjusting the position where theintake unit is supported by the covering makes it possible to adjust therelationship between the relative positions of the intake unit and thecovering. This makes it possible to readily mount the recessed reservoirunit and the intake unit at proper positions, by mounting the coveringsupporting the intake unit onto the fuel tank after having adjusted theposition where the intake unit is supported by the covering.

In the foregoing configuration, preferably, the covering is constitutedof a cylindrical body having a hollow space that communicates with therecessed reservoir unit, and a lower end of the cylindrical body isformed so as to be smaller than the recessed reservoir unit when seen inplan view and is inserted into the interior of the recessed reservoirunit.

According to this configuration, because the cylindrical body serving asthe covering is arranged so that the lower end thereof is inserted intothe interior of the recessed reservoir unit, the presence of thecylindrical body having been inserted into the interior of the recessedreservoir unit makes it possible to prevent swinging of the liquid levelof the fuel that is collected in the recessed reservoir unit, even whenthe fuel tank is swung in the left/right direction and the front/reardirection. It is accordingly possible to reliably prevent the fuel thatis collected in the recessed reservoir unit from flowing outwardlytherefrom. Moreover, the fuel can also be collected in the hollow spaceof the cylindrical body inserted into the interior of the recessedreservoir unit, thus making it possible to ensure a correspondinglygreater capacity of fuel that is taken in by the intake unit.

In the foregoing configuration, preferably, an air discharge unitenabling air in the hollow space to be discharged to the exterior of thecylindrical body is provided to an upper site of the cylindrical body.

According to this configuration, even when air is included in the fuelthat is collected in the recessed reservoir unit, it is possible for theair to rise through the hollow space of the cylindrical body and bedischarged to the exterior of the cylindrical body by the air dischargeunit. This makes it possible to remove air by using the cylindricalbody, and therefore makes it possible to properly prevent air from beingtaken in by the intake unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a device for supplyingfuel to an engine;

FIG. 2 is a front view of a merge and discharge unit;

FIG. 3 is a side view of a merge and discharge unit;

FIG. 4 is a side view of a tractor;

FIG. 5 is a schematic view illustrating an arrangement position of amerge and discharge unit in a tractor;

FIG. 6 is a side view of a tractor;

FIG. 7 is a plan view illustrating the inside of a cabin;

FIG. 8 is a perspective view of a fuel tank;

FIG. 9 is a cross-sectional view of a fuel tank;

FIG. 10 is a perspective view illustrating the main parts of a fueltank;

FIG. 11 is a perspective view illustrating the arrangement of a varietyof operation levers in a cabin;

FIG. 12 is a cross-sectional view illustrating the main parts of anauxiliary control lever;

FIG. 13 is a suction structure of a fuel tank in a separate embodiment;and

FIG. 14 is a suction structure of a fuel tank in a separate embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Embodiments of a fuel supply device for an engine as in the presentinvention shall be described on the basis of the accompanying drawings.

A fuel supply device 1 for an engine, as illustrated in FIG. 1, isprovided with a fuel supply route 4 for supplying to an engine 3 fuelthat is collected in a fuel tank 2. Provided to the fuel supply route 4are a moisture removal unit 5, an electromagnetic pump 6 (equivalent toa second fuel pump), a merge and discharge unit 7, a cooling unit 8, afeed pump 9 (equivalent to a third fuel pump), a filter 10, and a supplypump 11 (equivalent to a first fuel pump), in the stated order from theupstream side in a fuel supply direction.

The engine 3 is, for example, a common-rail diesel engine provided witha rail 3 a and a plurality of injectors 3 b, and is adapted to becapable of electronically controlling the amount of fuel injection andthe injection timing. The moisture removal unit 5 is, for example, asedimenter, and is adapted to remove moisture that is included in thefuel. The merge and discharge unit 7 is adapted to merge and dischargefuel flows. The cooling unit 8 is, for example, a cooler, and is adaptedto cool the fuel. The filter 10 is adapted to remove impurities that areincluded in the fuel.

The fuel of the fuel supply route 4 firstly undergoes moisture removalby the moisture removal unit 5 and is pressurized by the electromagneticpump 6, supplied to the cooling unit 8, and cooled in the cooling unit 8to a desired temperature range. The fuel, having reached the desiredtemperature range, is pressurized by the feed pump 9 and is supplied tothe filter 10; the impurities are removed by the filter 10. The fuelfrom which the impurities have been removed is pressurized by the supplypump 11 and supplied to the rail 3 a of the common-rail engine 3.

In the fuel supply device 1, not only is the fuel supplied to the engine3 via the fuel supply route 4, but also provided are a first fuel returnroute 12 via which the fuel of the engine 3 is returned to the merge anddischarge unit 7 and a second fuel return route 13 via which the fueldischarged from the merge and discharge unit 7 is returned to the fueltank 2. Herein, the fuel of the engine 3 that returns to the merge anddischarge unit 7 by way of the first fuel return route 12 is an amountcommensurate with the surplus with respect to the amount that isrequired in the engine 3, and would be, for example, surplus fuel fromthe rail 3 a and injector 3 b of the common-rail engine 3 as well assurplus fuel from the supply pump 11.

The configuration of such description thus, by being provided with thefirst fuel return route 12 and the second fuel return route 13, makes itpossible for the surplus fuel in the engine 3 to be returned to the fueltank 2 by way of the first fuel return route 12, the merge and dischargeunit 7, and the second fuel return route 13. Further, by being providedwith the merge and discharge unit 7, the configuration also makes itpossible to merge one portion of the surplus fuel in the engine 3 withthe fuel from the fuel tank 2 and to circulate the resulting confluencefor supply to the engine 3, as well as to return to the fuel tank 2 aremaining portion surplus fuel in the engine 3.

The merge and discharge unit 7 shall now be described.

As illustrated in FIG. 1, there are four flow paths that are connectedto the merge and discharge unit 7, namely, that of an upstream site 4 afurther upstream than the merge and discharge unit 7 in the fuel supplyroute 4, that of the first fuel return route 12, that of a downstreamsite 4 b further downstream than the merge and discharge unit 7 in thefuel supply route 4, and that of the second fuel return route 13.

The merge and discharge unit 7 accepts and merges fuel from the upstreamsite 4 a of the fuel supply route 4 and fuel from the first fuel returnroute 12, and discharges the merged fuels to the downstream site 4 b ofthe fuel supply route 4 and to the second fuel return route 13.

As illustrated in FIGS. 2 and 3, the merge and discharge unit 7 isprovided with: a reservoir unit 14 in which fuel can be collected; afirst merge unit 15 for merging into the reservoir unit 14 the fuel fromthe upstream site 4 a of the fuel supply route 4; a second merge unit 16for merging into the reservoir unit 14 the fuel from the first fuelreturn route 12; a first discharge unit 17 for discharging a portion ofthe fuel of the reservoir unit 14 into the downstream site 4 b of thefuel supply route 4; and a second discharge unit 18 for discharging aremaining portion of the fuel of the reservoir unit 14 into the secondfuel return route 13. FIG. 2 is a front view of the merge and dischargeunit 7, and FIG. 3 is a side view of the merge and discharge unit 7.

The merge and discharge unit 7 is configured by combining a recessedmember and a planar member, a hollow space in the shape of a cuboidbeing formed in the interior thereof; the hollow space serves as thereservoir unit 14. The reservoir unit 14 is formed in a vertically longshape, of greater length in the vertical direction, and is adapted to becapable of collecting enough to be capable of ensuring a fuel flow raterequired by the engine 3. A hole part 19 for attachment is also providedto both lateral sides of the reservoir unit 14; inserting and fasteninga bolt to the hole parts 19 for attachment enables attachment to adesired location.

The first merge unit 15, the second merge unit 16, the first dischargeunit 17, and the second discharge unit 18 are all formed in acylindrical shape, a hollow space in the interior thereof being incommunication with the reservoir unit 14. Further, the first merge unit15, the second merge unit 16, and the first discharge unit 17 arearranged at sites on the lower side of the reservoir unit 14 (a lowerend), and the second discharge unit 18 is arranged at a site on theupper side of the reservoir unit 14 (an upper end). This gives aconfiguration such that air that is included in the fuel rises to thesite on the upper side of the reservoir unit 14 and is discharged fromthe second discharge unit 18. Thus, though air may be included in thefuel being supplied to the engine 3, it is accordingly possible toremove air in the merge and discharge unit 7.

Holes in the cylindrical sites of the first merge unit 15, the secondmerge unit 16, and the first discharge unit 17 are formed at a firsthole diameter, and a hole in the cylindrical site of the seconddischarge unit 18 is formed to a second hole diameter that is smallerthan the first hole diameter. The second discharge unit 18 is therebyprovided with a constricted site where the flow path cross-sectionalarea is smaller than that of the first discharge unit 17, and providingthe constricted site of such description gives a configuration such thatthe amount of fuel discharged from the second discharge unit 18 is lessthan the amount of fuel discharged from the first discharge unit 17.

Herein, adjusting the extent to which the second hole diameter issmaller than the first hole diameter makes it possible to adjust theextent to which the amount of fuel discharged from the second dischargeunit 18 is less than the amount of fuel discharged from the firstdischarge unit 17. Thus, merely the simple adjustment of adjusting thehole diameter makes it possible to adjust the magnitude of flow ratesfor the amount of fuel being supplied to the engine 3 from the merge anddischarge unit 7 and for the amount of fuel being returned to the fueltank 2 from the merge and discharge unit 7.

The flow of fuel in the fuel supply device 1 shall now be described.

As illustrated in FIG. 1, the fuel of the fuel tank 2 is supplied to theengine 3 by way of the fuel supply route 4, and surplus fuel in theengine 3 is returned to the merge and discharge unit 7 of the fuelsupply route 4 by way of the first fuel return route 12. Then, in themerge and discharge unit 7, the surplus fuel in the engine 3 is suppliedby the second merge unit 16 to the reservoir unit 14 and the fuel of thefuel tank 2 is supplied by the first merge unit 15 to the reservoir unit14, the surplus fuel and the fuel being merged together and collected inthe reservoir unit 14. The fuel collected in the reservoir unit 14 isdischarged from both the first discharge unit 17 and the seconddischarge unit 18. Thereby, in the merge and discharge unit 7, the fuelfrom the fuel tank 2 supplied by the upstream site 4 a of the fuelsupply route 4 is merged into the surplus fuel having been returned bythe first fuel return route 12; a portion of the merged fuel is suppliedto the engine 3 by the downstream site 4 b of the fuel supply route 4,and a remaining portion of the fuel is returned to the fuel tank 2 bythe second fuel return route 13.

Thus, merely by providing the merge and discharge unit 7 to a sitebetween the fuel tank 2 and the filter 10 in the fuel supply route 4makes it possible to merge the surplus fuel in the engine 3 into thefuel from the fuel tank 2 and supply the merged fuels to the filter 10.Even at such times as the initial start-up of the engine 3 in a coldclimate, it is accordingly possible to merge fuel that has been heatedby heat generated from the engine 3 or the like into the low-temperaturefuel from the fuel tank 2 and supply comparatively high-temperature fuelto the filter 10, thus making it possible to prevent clogging of thefilter 10.

Because the fuel flow rate that is supplied to the merge and dischargeunit 7 by the upstream site 4 a of the fuel supply route 4 is an amountcorresponding to the fuel flow rate that is returned to the fuel tank 2from the merge and discharge unit 7, causing the amount of fueldischarged from the second discharge unit 18 to be less than the amountof fuel discharged from the first discharge unit 17 in the merge anddischarge unit 7 makes it possible to also lessen the fuel flow ratebeing supplied to the merge and discharge unit 7 from the fuel tank 2.It is accordingly possible to properly increase the fuel temperature ofthe fuel being supplied to the filter 10, and possible to reliablyprevent clogging of the filter 10.

Also, because the amount of fuel being supplied to the merge anddischarge unit 7 from the upstream site 4 a of the fuel supply route 4can be lessened, the flow rate intended to be processed by the moistureremoval unit 5 can be lessened, making it possible to reduce theprocessing capability required for the moisture removal unit 5, and alsothe required capacity for the electromagnetic pump 6 can be reduced. Itis accordingly possible to successfully lower the sizes and costs of themoisture removal unit 5 and the electromagnetic pump 6.

The fuel that is returned to the merge and discharge unit 7 by way ofthe first fuel return route 12 is surplus fuel in the engine 3, and thissurplus fuel is supplied in circulation to the engine 3, and thus thereis the possibility that when the engine 3 is continuously operated, thefuel temperature of the fuel being supplied to the engine 3 maygradually rise and reach an excessively high level. In view whereof,because in the fuel supply route 4 the cooling unit 8 is arrangedfurther downstream than the merge and discharge unit 7 in the fuelsupply direction, the fuel that is discharged from the merge anddischarge unit 7 to the downstream site 4 b of the fuel supply route 4can be cooled to a desired temperature range by the cooling unit 8, thuspreventing the fuel temperature of the fuel being supplied to the engine3 from reaching an excessively high level.

The fuel supply device 1 of the engine in the present embodiment isadapted for a work vehicle such as a tractor 100, as is illustrated inFIG. 4. The tractor 100 is of a four-wheel drive format, provided with atraveling vehicle body 103 having a pair of left and right front wheels101 that can be driven and operated by steering and a pair of left andright rear wheels 102 that can be driven. A hood 104 in which the engine3 and the like are housed is provided to the front of the travelingvehicle body 103, and a cabin 107 on which a steering handle 105, seat106, and the like are housed is provided to the rear of the travelingvehicle body 103.

A main frame 108 extends forward from a lower part of the engine 3, andan axle case (not shown) onto which the front wheels 101 are mounted andthe like are supported at the main frame 108. A clutch housing 109extends rearward from the engine 3, and a transmission case 110 locatedbelow the seat 106 is coupled to the clutch housing 109, theconfiguration being such that the power from the engine 3 is transmittedto the rear wheels 102.

Provided to the rear of the traveling vehicle body 103 are a linkmechanism 111, constituted of a pair of left and right lift arms, and apower take-off shaft 112. Such is the configuration that coupling arotary tilling device (not shown) or the like to the link mechanism 111so as to be vertically operable and interlockingly coupling the rotarytilling device or the like to the power take-off shaft 112 makes itpossible to vertically operate and drive the rotary tilling device orthe like.

In the fuel supply device 1, as illustrated in FIG. 5, housed within thehood 104 are the moisture removal unit 5, the electromagnetic pump 6,the merge and discharge unit 7, the cooling unit 8, the feed pump 9, thefilter 10, and the supply pump 11.

FIG. 5 is a side view in which the interior of the hood 104 is viewedfrom the right side; the moisture removal unit 5, the electromagneticpump 6, the merge and discharge unit 7, the feed pump 9, the filter 10,and the supply pump 11 are arranged on the right side of the engine 3.

As illustrated in FIG. 4, the fuel tank 2 is arranged below a floorpanel 113 that forms the floor of the cabin 107. Although not shown inthe drawings, the fuel tank 2 is provided as a left/right pair, with afirst fuel tank arranged on the right side of the cabin 107 and a secondfuel tank arranged on the left side thereof. A fuel replenishment portis provided to the first fuel tank, the configuration being such thatfuel is supplied from the first fuel tank to the second fuel tank by wayof an interconnecting path. Intake of the fuel from the fuel tank 2involves taking in fuel from the second fuel tank and supplying thetaken-in fuel to the engine 3 by the fuel supply route 4.

As illustrated in FIG. 5, the merge and discharge unit 7 is fixed to thesupport member 114 by the bolt being inserted and fastened to the holepart 19 for attachment, and the position for arranging same is aposition high up on the right side than the engine 3. This makes itpossible for the position for arranging the merge and discharge unit 7to be a high position, thus making it possible, even when air isincluded in the fuel collected in the reservoir unit 14, for the air torise and be discharged from the second discharge unit 18, allowing forproper removal of air in the merge and discharge unit 7. In regardthereto, the height at which the merge and discharge unit 7 is arrangedis a position that is higher than those of the moisture removal unit 5,the electromagnetic pump 6, the feed pump 9, the filter 10, the supplypump 11, and the like.

Other Embodiments

(1) In the foregoing embodiment, for example, arranging the fuel tank 2farther up than the moisture removal unit 5, the cooling unit 8, or thelike makes it possible to forgo the electromagnetic pump 6 (which isequivalent to a second fuel pump). Also, beyond the electromagnetic pump6, it would furthermore be possible to forgo the cooling unit 8 or thefeed pump 9; of these three devices, any one or two can be forgone, orall.

(2) In the foregoing embodiment, it would also be possible for theposition where the merge and discharge unit 7 is arranged in the fuelsupply route 4 to be located between the moisture removal unit 5 and theelectromagnetic pump 6.

(3) In the foregoing embodiment, causing the flow path cross-sectionalarea of the second fuel return route 13 to be smaller than that of thedownstream site 4 b in fuel supply route 4 makes it possible to provideto the second fuel return route 13 a constricted site of lesser flowpath cross-sectional area than that of the downstream site 4 b in thefuel supply route 4. Providing the constricted part of such descriptionalso makes such a configuration possible that the amount of fueldischarged from the second discharge unit 18 is less than the amount offuel discharged from the first discharge unit 17.

Also, as regards the constricted site, there is no restriction to beingone where the flow path cross-sectional area is adjusted; providing aconstriction such as an orifice would also make it possible to provide aconstricted site.

(4) In the foregoing embodiment, the full amount of surplus fuel of theengine 3 was returned to the merge and discharge unit 7 by the firstfuel return route 12, but it would also be possible to provide, forexample, a connecting flow path for fuel return that connects togetherthe fuel tank 2 and a midway site of the first fuel return route 12, sothat a portion of the surplus fuel of the engine 3 is returned to themerge and discharge unit 7 by the first fuel return route 12 and aportion of the remaining surplus fuel of the engine 3 is returneddirectly to the fuel tank 2 by the connecting flow path for fuel return.

(5) The foregoing embodiment illustrates an example where the fuelsupply device for an engine as in the present invention is adapted tothe tractor 100 for agricultural use, but adaptation to a variety ofother work vehicles would also be possible.

Second Embodiment

An example where an intake structure for a fuel tank as in the presentinvention has been adapted to a tractor shall now be described, on thebasis of the accompanying drawings.

This tractor 201, as illustrated in FIG. 6, is constituted of afour-wheel drive format, provided with a traveling vehicle body 204having a pair of left and right front wheels 202 that can be driven andoperated by steering and a pair of left and right rear wheels 203 thatcan be driven. A hood 206 in which an engine 205 and the like are housedis provided to the front of the traveling vehicle body 204, and a cabin209 on which a steering handle 207, a seat 208, and the like are housedis provided to the rear of the traveling vehicle body 204.

A main frame 210 extends forward from a lower part of the engine 205,and an axle case (not shown) onto which the front wheels 202 are mountedand the like are supported at the main frame 210. A clutch housing 211extends rearward from the engine 205, and a transmission case 212located below the seat 208 is coupled to the clutch housing 211, theconfiguration being such that the power from the engine 205 istransmitted to the rear wheels 203.

Provided to the rear of the traveling vehicle body 204 are a linkmechanism 213, constituted of a pair of left and right lift arms, and apower take-off shaft 214. Such is the configuration that coupling arotary tilling device (not shown) or the like to the link mechanism 213so as to be vertically operable and interlockingly coupling the rotarytilling device or the like to the power take-off shaft 214 makes itpossible to vertically operate and drive the rotary tillage device orthe like.

Housed within the transmission case 212 are, for example, a gear-typetransmission device and a stepless transmission device such as ahydrostatic stepless transmission device, though a depiction thereof hasbeen forgone; power taken out from the engine 205 is transmitted to thestepless transmission device via a main clutch (not shown) or the like.Of the power that is taken out from the stepless transmission device,power for traveling is transmitted to the left and right front wheels202 and to the left and right rear wheels 203 via the gear-typetransmission device. Of the power that is taken out from the steplesstransmission device, also, power for working is transmitted to the powertake-off shaft 214 via an action clutch (not shown) or the like.

The cabin 209, as illustrated in FIGS. 6 and 7, is configured to beprovided with: a cabin frame 215; a front windshield 216 for coveringthe front surface of the cabin frame 215; a door 217 provided to anentry on two sides of the cabin frame 215; a side windshield 218provided to the rear of the door 217; and a rear windshield 219 forcovering the rear surface of the cabin frame 215.

The cabin frame 215 is provided with: a support frame 22, in the shapeof a square pipe, for supporting the cabin 209; a lower frame 221coupled to the support frame 220; and an upper frame 222. Between thelower frame 221 and the upper frame 222, a pair of left and rightA-posts 223 are provided to the front end thereof, a pair of left andright B-posts 224 are provided to the middle thereof, and a pair of leftand right C-posts 225 are provided to the rear end thereof. The A-posts223, the B-posts 224, and the C-posts 225 are each coupled by the upperend to the upper frame 222 and by the lower end to the lower frame 221.

The lower side of the cabin frame 215 is equipped with a floor panel 226that forms the floor of the cabin 209, and a rear wheel fender 227formed in a shape that covers the outer periphery of the rear wheels 203from above is fixed to both left and right sides of the floor panel 226.The floor panel 226 is configured to be provided with a step floor panel226 a for the front of the cabin 209 and a seat floor panel 226 b forthe rear of the cabin 209, the seat 208 being disposed at the left/rightmiddle of the seat floor panel 226 b.

The steering handle 207, as illustrated in FIG. 7, is supported at thefront of the cabin 209. The front windshield 216 is mounted across theleft and right A-posts 223, and the front surface of the cabin frame 215is covered by the front windshield 216. The rear windshield 219 ismounted across the left and right C-posts 225, and the rear surface ofthe cabin frame 215 is covered by the rear windshield 219. The doors 217are mounted onto the entries on both sides of the cabin frame 215 formedacross the A-posts 223 and the B-posts 224, so that the doors can beslid open about an axis of the rear end; the side windshields 218 aremounted across the B-posts 224 and the C-posts 225 so that the sidewindshields can be slid open.

Fuel tanks 228 for collecting fuel to be supplied to the engine 205, asillustrated in FIGS. 6 and 7, are arranged below the step floor panel226 a in the floor panel 26 that forms the floor of the cabin 209. Thefuel tanks 228, as illustrated in FIG. 8, are provided as a left/rightpair, with a first fuel tank 228 a arranged on the right side of thecabin 209 and a second fuel tank 228 b arranged on the left sidethereof. The first fuel tank 228 a and the second fuel tank 228 b areeach supported by the traveling vehicle body 204 via a frontal supportbracket 231 provided to a frontal site thereof and via a rear supportbracket 232 provided to a rear site thereof.

A fuel replenishment unit 229 is provided to the first fuel tank 228 a,and a communicating part that interconnects the first fuel tank 228 aand the second fuel tank 228 b is provided. Fuel being replenished fromthe fuel replenishment unit 229 is thereby supplied to the first fueltank 228 a, passed through the communicating part 230 from the firstfuel tank 228 a, and supplied also to the second fuel tank 228 b. Thecommunicating part 230 is provided with a check valve (not shown) thatallows fuel to flow through from the first fuel tank 228 a to the secondfuel tank 228 b and checks against flow of fuel through from the secondfuel tank 228 b to the first fuel tank 228 a. The communicating part 230is covered by a cover body 233, of concave cross-section, that coversthe front side thereof, the rear side thereof, and the bottom sidethereof.

The first fuel tank 228 a and the second fuel tank 228 b are constitutedof a resin that has been molded by blow molding. The first fuel tank 228a and the second fuel tank 228 b are provided with a stepped part so asto be of different height at the upper end thereof, and are formed in ashape that is longer in the front/rear direction when seen in plan view.The first fuel tank 228 a and the second fuel tank 228 b, as illustratedin FIGS. 7 and 8, are formed in a curved shape so that an outside siteof the rear end site thereof runs along the shape of the front end siteof the rear wheel fender 227, as seen in plan view, and the rear endsite thereof is configured so as to extend further rearward than thefront end of the rear wheel fender 227. The first fuel tank 228 a andthe second fuel tank 228 b are thus adapted to be capable of ensure agreater capacity while also making effective use of the space below thestep floor panel 226 a.

In the present embodiment, an intake structure 300 for a fuel tank isprovided to the second fuel tank 228 b, the configuration being suchthat fuel that has been taken in by the intake structure 300 is suppliedto the engine 205 by way of a fuel supply route 234. A fuel return route235 for returning to the fuel tanks 228 fuel from the engine 205 isconnected to the first fuel tank 228 a.

The following describes the intake structure 300.

The intake structure 300, as illustrated in FIG. 9, is provided with: anintake unit 301 for taking in and drawing out fuel N of the second fueltank 228 b, above the bottom of the second fuel tank 228 b; a recessedreservoir unit 302 that is arranged at the bottom of the second fueltank 228 b, is recessed so as to be lower than same, and is able tocollect the fuel N; and a covering 303 for covering the recessedreservoir unit 302 in a state where the fuel N is permitted to flow intothe recessed reservoir unit 302. The intake unit 301 is adapted to takein and draw out the fuel N that has been collected in the recessedreservoir unit 302.

FIG. 9 is a cross-sectional view in which the second fuel tank 228 b isseen from the rear in FIG. 10; as illustrated in FIG. 9, the second fueltank 228 b is formed in a shape where an upper site 228A of the outsidethereof is projected outward, and the bottom thereof is formed so as tobe stepped, having a stepped part 228D between an outer bottom 228B andan inner bottom 228C.

The recessed reservoir unit 302 is provided to the inner bottom 228C,which is located bottommost on the bottom of the second fuel tank 228 b.The recessed reservoir unit 302 is arranged at a position close to thestepped part 228D on the inner bottom 228C, and is arranged at aposition where the fuel N readily flows in at the curved stepped part228D. The recessed reservoir unit 302, as illustrated in FIG. 10, isformed in a circular shape when seen in plan view, and an inner wallpart 302 a thereof is formed in an inclined shape, where a lower site islocated further inward than is an upper site.

The covering 303, as illustrated in FIGS. 9 and 10, is constituted of acircular cylindrical body 303 a having a hollow space that hascommunication with the recessed reservoir unit 302, and the lower end ofthe cylindrical body 303 a is formed so as to be smaller than therecessed reservoir unit 302 when seen in plan view and is inserted intothe interior of the recessed reservoir unit 302. Because the recessedreservoir unit 302 and the covering 303 are both formed so as to becircular, the outer diameter of the covering 303 is configured so as tobe smaller than the inner diameter of the recessed reservoir unit 302.The covering 303 is arranged at a middle site of the recessed reservoirunit 302 when seen in plan view, the configuration being such that themiddle site of the recessed reservoir unit 302 is covered by thecovering 303.

This manner of arranging the covering 303 makes it possible to form aspacing K1 between an outer wall part of the covering 303 and the innerwall part 302 a of the recessed reservoir unit 302, across the fulllength of the outer periphery of the covering 303. Accordingly, coveringthe middle site of the recessed reservoir unit 302, as seen in planview, with the covering 303, while also allowing the fuel N to flow intothe recessed reservoir unit 302 from the spacing K1, prevents the fuel Nfrom flowing outwardly from the recessed reservoir unit 302.

The covering 303 is configured to be provided with the circularcylindrical body 303 a, the interior of which is a hollow space, and isarranged so that the lower end of the cylindrical body 303 a extends outto the interior of the recessed reservoir unit 302. Thus, even when thetraveling vehicle body 204 is swung in the front/rear direction and theleft/rear direction, the presence of the cylindrical body 303 a preventsthe liquid level of the fuel N that has been collected in the recessedreservoir unit 302 from swinging. Moreover, as illustrated in FIG. 9,the fuel N can be collected in the hollow space of the interior of thecylindrical body 303 a, as well, and a correspondingly greater capacityof fuel taken in by the intake unit 301 can be ensured. It is thuspossible for the fuel N having been collected in the recessed reservoirunit 302 to flow out therefrom, while a greater capacity of fuel N takenin by the intake unit 301 can also be ensured; an event where no fuel Nremains in the lower end of the intake unit 301 and where air is takenin at the intake unit 301 can be properly prevented.

The intake unit 301 is constituted of a tubular body supported by thecovering 303, and is disposed extending upward and downward through theinterior space of the hollow of the covering 303. The lower end of theintake unit 301 is given substantially the same height as the lower endof the covering 303, and is inserted into the interior of the recessedreservoir unit 302. The intake unit 301 is arranged at a positionshifted further toward the outer periphery than the middle, as seen inplan view, in the circular cylindrical body 303 a in the covering 303.

Herein, for example, the lower ends of the intake unit 301 and of thecovering 303 are arranged at a vertically intermediate part of therecessed reservoir unit 302. The spacing K1 between the outer wall partof the covering 303 and the inner wall part 302 a of the recessedreservoir unit 302 is configured so as to be smaller than a spacing K2that is between the bottom of the recessed reservoir unit 302 and thelower ends of the intake unit 301 and of the covering 303.

This makes it possible to properly prevent the collected fuel N fromflowing outwardly therefrom, while also making it possible to collecteven more of the fuel N.

The covering 303, as has been described above, is constituted of thecircular cylindrical body 303 a, but is provided with a cover body 303 bfor closing off an upper part of the cylindrical body 303 a. The coverbody 303 b is configured to be of a disc shape of greater diameter thanthat of the cylindrical body 303 a, and a site projecting furtheroutward than the cylindrical body 303 a serves as an attachment site forthe second fuel tank 228 b. A circular opening part permitting insertionand removal of the cylindrical body 303 a is formed at the upper surfaceof the second fuel tank 22 b, the configuration being such that thecovering 303 is mounted onto the second fuel tank 228 b by inserting andfastening a bolt to a hole part of the attachment site of the cover body303 b in a state where the cylindrical body 303 a has been inserted intothe opening part. The intake unit 301 is supported by the covering 303in a state of penetrating through the cover body 303 b, and is adaptedto enable insertion and removal of the cover body 303 supporting theintake unit 301, into/from the second fuel tank 228 b.

Provided to an upper site of the cylindrical body 303 a are a pluralityof communicating holes 304 creating communication between a hollow spaceof the interior thereof and the exterior thereof. The plurality ofcommunicating holes 304 are arranged dispersed in the peripheraldirection and up/down direction of the cylindrical body 303 a. Thisgives such a configuration that even when air is included in the fuel Nthat is collected in the recessed reservoir unit 302, the air risesthrough the hollow space of the cylindrical body 303 a and is dischargedto the exterior of the cylindrical body 303 a at the communicating holes304. Also provided to the cover body 303 b is an exterior communicatingpart 305 that penetrates therethrough and creates communication betweenthe hollow space of the interior of the cylindrical body 303 a and theexterior of the second fuel tank 228 b. The exterior communicating part305 is adapted to discharge to the exterior of the second fuel tank 228b air that has risen through the hollow space. The communicating holes304 and the exterior communicating part 305 are thus provided to theupper site of the cylindrical body 303 a, as an air discharge unitcapable of discharging the air of the hollow space to the exterior ofthe cylindrical body 303 a. Thus, even when air is included in the fuelN having been collected in the recessed reservoir unit 302, it ispossible to properly remove the air, and more reliably prevent the airfrom being taken in at the intake unit 301.

Coupling of a front loader to the front of the traveling vehicle body204, though a depiction thereof has been omitted, enables the tractor201 configured in this manner to, for example, carry out work suchexcavating earth and sand or transporting and transferring the earth andsand to a desired location such as a track, and the like. In addition toa rotary tilling device that can be interlockingly coupled to the powertake-off shaft 214, the configuration also permits mounting of a varietyof other work devices, depending on the work, to the rear of thetraveling vehicle body 204. Also, though a depiction has been omitted, aplurality (for example, three) of auxiliary control valves are providedto the rear of the traveling vehicle body 204, in the vicinity of ahydraulic device of the link mechanism 213 or the like, and therefore incases where a variety of work devices are mounted the configurationmakes it possible to couple hydraulic control machinery for the workdevice to the auxiliary control valves and hydraulically control thework device.

The tractor 201 is thus adapted to be capable of carrying out a varietyof tasks, by coupling the front loader to the front of the travelingvehicle body 204 or by coupling a variety of work devices to the rear ofthe traveling vehicle body 204. Also provided inside the cabin 209 are avariety of operation levers, such as an operation lever for causing thetraveling vehicle body 204 to travel, as well as an operation lever formanually operating the front loader and an operation lever for manuallyoperating the work devices.

A variety of operation levers disposed inside the cabin 209 shall now bedescribed.

As illustrated in FIGS. 7 and 11, a variety of operation levers aredisposed in concentration above the rear wheel fender 227 on the rightside of the seat 208. FIG. 11 is a perspective view illustrating theright side of the seat 208 of the cabin 209. Provided as operationlevers are: a hand accelerator lever 236 for manually operating theaccelerator; a loader lever 237 for the front loader; a draft lever 238for setting a work load in a draft control for maintaining a constantwork load; a position lever 239 for carrying out positional controlvertically moving the link mechanism 213; and auxiliary control levers240, 241, 242 for operating the auxiliary control valves. As regards theauxiliary control levers, three auxiliary control valves are provided tothe rear of the traveling vehicle body 204, as is described above, andthus there are three operating levers provided, namely, a firstauxiliary control lever 240, a second auxiliary control lever 241, and athird auxiliary control lever 242.

Also, in addition to the variety of operation levers 236 to 242, a powertake-off switch 243 for switching the power take-off shaft 214 between adrive state and a non-drive state is also disposed on the right side ofthe seat 208.

The following describes the arrangement positions, configurations, andthe like of the variety of operation levers 236 to 242. The “left/rightdirection” is understood to be the left/right direction of the travelingvehicle body 204 (the X direction in FIGS. 7 and 11), and the“front/rear direction” is understood to be the front/rear direction ofthe traveling vehicle body 204 (the Y direction in FIGS. 7 and 11).

Among the variety of operation levers, the hand accelerator lever 236 isarranged at a position closest to the seat 208 in the left/rightdirection (the X direction). A first installation surface 244 forinstalling the hand accelerator lever 236 is formed atop the rear wheelfender 227. The first installation surface 244 is formed in an inclinedshape that extends in the front/rear direction (the Y direction) andbecomes increasingly lower going forward. The hand accelerator lever 236is provided so as to be able to swing forward and back along a firstguide 245 extending in the front/rear direction (the Y direction),formed on the first installation surface 244.

The loader lever 237 is arranged further forward than the handaccelerator lever 236, on the side further apart from the seat 208 thanthe hand accelerator lever 236 in the left/right direction (the Xdirection). The loader lever 237 is configured in a vertically orientedcross-shape permitting swinging in the front/rear direction (the Ydirection) and the left/right direction (the X direction). The loaderlever 237 is arranged so that a rearward region of the swing range inthe front/rear direction (the Y direction) thereof is lined up in theleft/right direction (the X direction) with a forward region of theswing range in the front/rear direction (the Y direction) of the handaccelerator lever 236.

The draft lever 238 and the position lever 239 are both arranged, in astate where the two levers are lined up together in the left/rightdirection (the X direction), further rearward than the loader lever 237,on a side further apart from the seat 208 than the hand acceleratorlever 236 in the left/right direction (the X direction). A secondinstallation surface 246 for installing the draft lever 238 and theposition lever 239 is formed atop the rear wheel fender 227, and thesecond installation surface 246 is adapted so as to be one step higherthan the first installation surface 244. A second guide 247 and a thirdguide 248 that are further inclined at the front side toward the sidethat is apart from the seat 208 in the left/right direction (the Xdirection) are formed on the second installation surface 246, and thedraft lever 238 and the position lever 239 are provided so as to be ableto swing along the second guide 247 and the third guide 248.

The power take-off switch 243 is arranged on the rear side of the handaccelerator lever 236. A third installation surface 249 for installingthe power take-off switch 243 is formed. The third installation surface249 is formed in a curved shape that is lower than the firstinstallation surface 244 and extends in the front/rear direction, andthe power take-off switch 243 is provided to the third installationsurface 249 and adapted to be press-operable.

The auxiliary control levers 240 to 242 are arranged further rearwardthan the draft lever 238 and the position lever 239, on a side that isfurther apart from the seat 208 than the draft lever 238, the positionlever 239, and the power take-off switch 243 in the left/right direction(the X direction). A fourth installation surface 250 for installing thefirst auxiliary control lever 240 and the second auxiliary control lever241 is formed, and a fifth installation surface 251 for installing thethird auxiliary control lever 242 is formed. The fourth installationsurface 250 is provided with a stepped part relative to the rear end ofthe second installation surface 246, and is formed at a higher positionthan that of the second installation surface 246 in an inclined shapethat becomes lower going forward. A fourth guide 252 and a fifth guide253 extending in the front/rear direction (the Y direction) are formedon the fourth installation surface 250 in a state of being lined uptogether in the left/right direction (the X direction), and the firstauxiliary control lever 240 and the second auxiliary control lever 241are provided so as to be able to slide along the fourth guide 252 andthe fifth guide 253. The fifth installation surface 251 is a rearwardcontinuation from the fourth installation surface 250, and is formed inan inclined shape that becomes lower going rearward. A sixth guide 254that extends in the front/rear direction (Y direction) is formed on thefifth installation surface 251, and the third auxiliary control lever242 is provided so as to be able to slide along the sixth guide 254.

As regards the arrangement relationship of the three operation levers,i.e., the first through third auxiliary control levers 240 to 242, thefirst auxiliary control lever 240 and the second auxiliary control lever241 are lined up together in the left/right direction (the X direction),and the third auxiliary control lever 242 is arranged further rearwardthan the first auxiliary control lever 240 and the second auxiliarycontrol lever 241 on a side that is further apart from the seat 208 thanthe first auxiliary control lever 240 and the second auxiliary controllever 241 in the left/right direction (the X direction). In other words,the arrangement positions of the three operation levers, i.e., the firstthrough third auxiliary control levers 240 to 242, are arranged so as tobe in an L-shape when seen in plan view.

This manner of arranging the first through third auxiliary controllevers 240 to 242 prevents the third auxiliary control lever 242 frombecoming a hindrance when the driver operates the first auxiliarycontrol lever 240 or the second auxiliary control lever 241, andconversely also prevents the first auxiliary control lever 240 or thesecond auxiliary control lever 241 from becoming a hindrance when thedriver operates the third auxiliary control lever 242. Also, forexample, there is no need to ensure adequate installation space forlining up the three operation levers together in the left/rightdirection (the X direction), and this is beneficial in terms ofinstallation space. Moreover, because a comparatively greater left/right(X-direction) spacing is taken between the first auxiliary control lever240 and the second auxiliary control lever 241, the second auxiliarycontrol lever 241 is less likely to become a hindrance when the driveroperates the first auxiliary control lever 240 and the first auxiliarycontrol lever 240 is less likely to become a hindrance when the driveroperates the second auxiliary control lever 241.

Accordingly, the operability of the auxiliary control levers 240 to 242can be enhanced.

The first and second auxiliary control levers 240, 241 are pivotallysupported at proximal ends thereof, as illustrated in FIG. 12, and areprovided with a proximal end side 256 extending from a pivot support 255therefor and a distal end site 257 curved upward from the proximal endsite 256. The first and second auxiliary control levers 240, 241 arethereby adapted to have a large swing range in not only the front/reardirection but also in the up/down direction. The fifth installationsurface 251, which is formed in an inclined shape that becomes lowergoing rearward, is present at the rear side of the first and secondauxiliary control levers 240, 241. Therefore, the driver is readily ableto vertically swing the first and second auxiliary control levers 240,241 in a state where the wrist or the like is placed atop the fifthinstallation surface 251. The operability of the first and secondauxiliary control levers 240, 241 can accordingly be even furtherenhanced.

Other Embodiments

(1) In the foregoing embodiment, the covering 303 was constituted of thecylindrical body 303 a, but, for example, as illustrated in FIGS. 13 and14, the covering 303 could also be constituted of a planar body. In sucha case, as illustrated in FIGS. 13 and 14, supporting the covering 303on the intake unit 301 makes it possible to arrange the covering 303 ata desired location.

In FIG. 13, the planar body that is the covering 303 is formed in acircular shape of lesser diameter than that of the circular recessedreservoir unit 302, and is arranged so that a middle site of therecessed reservoir unit 302 as seen in plan view is covered with thecovering 303. Also, in FIG. 13, the covering 303 is inserted into theinterior of the recessed reservoir unit 302.

In FIG. 14, the planar body that is the covering 303 is formed in acircular shape of greater diameter than that of the circular recessedreservoir unit 302, and is arranged so that the entirety of the recessedreservoir unit 302 as seen in plan view is covered with the covering303. Also, in FIG. 14, the covering 303, spaced apart from the bottom ofthe fuel tanks, is arranged thereabove.

(2) In the foregoing embodiment, the fuel tank 228 is constituted of thefirst fuel tank 228 a and the second fuel tank 228 b, but, for example,a single fuel tank would also be possible, and the number thereof can bealtered as appropriate. Also, as regards the arrangement positions ofthe fuel tanks 228, there is no limitation to being below the step floorpanel 226 a; for example, arrangement in the interior of the hood 206would also be possible, and the arrangement positions thereof can bealtered as appropriate.

(3) In the foregoing embodiment, the arrangement position of thecovering 303 can be altered as appropriate. As stated in (1) above, asillustrated in FIG. 14, the entirety of the recessed reservoir unit 302as seen in plan view may be covered; in a case where a portion of therecessed reservoir unit 302 as seen in plan view is covered, there is nolimitation to the middle site being covered. Neither is the lower end ofthe covering 103 limited to being inserted into the interior of therecessed reservoir unit 302; the lower end of the covering 103 can bearranged, e.g., so as to become substantially flush with the bottom ofthe fuel tanks.

(4) In the foregoing embodiment, an example where the intake structurefor a fuel tank as in the present invention is adapted to the tractor201 is illustrated, but the intake structure may be adapted to a varietyof other work vehicles is also possible.

What is claimed is:
 1. A device for supplying fuel to an engine, thefuel supply device comprising: a fuel tank; a fuel supply route forsupplying to the engine fuel that has been collected in the tank; afilter provided to the fuel supply route; a first fuel pump provideddownstream of the filter in a fuel supply direction on the fuel supplyroute; a merge and discharge unit for merging and discharging fuel, themerge and discharge unit being provided to a site between the fuel tankand the filter on the fuel supply route; a first fuel return route forreturning the fuel of the engine to the merge and discharge unit; and asecond fuel return route for returning to the fuel tank the fueldischarged from the merge and discharge unit; wherein: the merge anddischarge unit has: a reservoir unit in which fuel can be collected; afirst merge unit for merging into the reservoir unit the fuel from asite upstream of the merge and discharge unit on the fuel supply route;a second merge unit for merging into the reservoir unit the fuel fromthe first fuel return route; a first discharge unit for discharging aportion of the fuel in the reservoir unit to a site downstream of themerge and discharge unit on the fuel supply route; and a seconddischarge unit for discharging a remaining portion of the fuel in thereservoir unit into the second fuel return route.
 2. The device forsupplying fuel to an engine as in claim 1, wherein: the amount of fueldischarged from the second discharge unit is less than the amount offuel discharged from the first discharge unit.
 3. The device forsupplying fuel to an engine as in claim 2, wherein: in causing theamount of fuel discharged from the second discharge unit to be less thanthe amount of fuel discharged from the first discharge unit, aconstricted site where the flow path cross-sectional area is less thanthat of the first discharge unit is provided to the second dischargeunit, or a constricted site where the flow path cross-sectional area isless than that of the downstream site on the fuel supply route isprovided to the second fuel return route.
 4. The device for supplyingfuel to an engine as in claim 1, wherein: the first merge unit, thesecond merge unit, and the first discharge unit of the merge anddischarge unit are arranged in sites below the reservoir unit, and thesecond discharge unit is arranged at a site above the reservoir unit. 5.The device for supplying fuel to an engine as in claim 1, wherein: amoisture removal unit for removing moisture included in the fuel isarranged at a site between the fuel tank and the merge and dischargeunit on the fuel supply route.
 6. The device for supplying fuel to anengine as in claim 1, wherein: a cooling unit for cooling the fuel isarranged at a site between the merge and discharge unit and the filteron the fuel supply route.
 7. The device for supplying fuel to an engineas in claim 1, wherein: a moisture removal unit for removing moistureincluded in the fuel, a second fuel pump, the merge and discharge unit,a cooling unit for cooling the fuel, a third fuel pump, the filter, andthe first fuel pump are provided to the fuel supply route in the statedorder from the upstream side in the fuel supply direction.
 8. A fuelsupply device for supplying fuel to an engine, the fuel supply devicecomprising: a fuel tank, the fuel tank including: a bottom; a recessedreservoir unit for collecting fuel, the recessed reservoir unit beingrecessed so as to be lower than other portions on the bottom; a coveringfor covering the recessed reservoir unit in a state where the fuel ispermitted to flow into the recessed reservoir unit; and an intake unitfor taking in and drawing out fuel inside the fuel tank, above thebottom of the fuel tank.
 9. The device for supplying fuel to an engineas in claim 8, wherein: the covering is adapted so as to cover a middlesite of the recessed reservoir unit as seen in plan view.
 10. The devicefor supplying fuel to an engine as in claim 8, wherein: the intake unitis supported by the covering, and is configured so that the coveringsupporting the intake unit can be inserted into or removed from the fueltank.
 11. The device for supplying fuel to an engine as in claim 8,wherein: the covering is constituted of a cylindrical body having ahollow space that communicates with the recessed reservoir unit, and alower end of the cylindrical body is formed so as to be smaller than therecessed reservoir unit when seen in plan view and is inserted into theinterior of the recessed reservoir unit.
 12. The device for supplyingfuel to an engine as in claim 11, wherein: an air discharge unitenabling air in the hollow space to be discharged to the exterior of thecylindrical body is provided to an upper site of the cylindrical body.